I have the Sony MDR-970R and they're not worth the time to recharge the battery. At first, I thought they were handy but they're a worthless piece of "you know what". After about 10-15 minutes, they give a loud POP and base unit shuts off. If the volume is up on the headset, it's enough to hurt your ears. I'm afraid to wear the things now. If you unplug the power and reconnect, it might last for another 30-60 minutes (or not) then it pops and shuts down again. I think it's over heating as the base seems to get pretty warm while in operation.
And, the sound quality is not very good. It has a syncing button and two or three presses will bring it in better but it still has a raspy sound. No amount of adjusting or distance changes the poor quality audio.